CHDK

The cameras are on order from eBay. The Canan A570 IS (image stabilized) arrived today. Looks in great condition. A weekend project will be to hack the camera using CHDK and check out the time-lapse modes. Then calculate the size of SD card needed for photographs throughout the flight. I have to learn how to boot into this, and set up a script for the time-lapse required:

• Do I go for a photo every 30s, 1min or longer?
• How do I preset 'infinite' focus?
• Must remember to plug the AV socket to turn off LCD display to save battery
• Will need to order some good Energizer Lithium's nearer flight time
• What's the best way of protecting against condensation on lens?

GPS

For this project I want to avoid any form of on-board computer. I'm using a tiny lite-weight GPS transponder I ordered from China.

Battery life seems incredible. After more than 2 days, both units I am testing still have 75% battery. The Li-Ion batteries are not good at low temperature according to some folks, but with good insulation I think they will be ok, especially for a "short" up and down flight.

My only concern is that one of the units seem less capable at picking up GPS than the other. This is evident by looking at the time stamp returned. I don't want false reporting. More testing 'outside' required.

Another issue to worry about in this type of flight is if the balloon lands in a mobile signal dead zone. To counteract this I will fit two different SIMs for two different mobile networks. Will this be enough to guarantee a signal?